Digital media playback capabilities may be incorporated into a wide range of devices, including digital televisions, including so-called “smart” televisions, set-top boxes, laptop or desktop computers, tablet computers, digital recording devices, digital media players, video gaming devices, cellular phones, including so-called “smart” phones, dedicated video streaming devices, and the like. Digital media content (e.g., video and audio programming) may originate from a plurality of sources including, for example, over-the-air television providers, satellite television providers, cable television providers, online media service providers, including, so-called streaming service providers, and the like. Digital media content may be delivered over packet-switched networks, including bidirectional networks, such as Internet Protocol (IP) networks and unidirectional networks, such as digital broadcast networks.
Digital media content may be transmitted from a source to a receiver device (e.g., a digital television or a smart phone) according to a transmission standard. Examples of transmission standards include Digital Video Broadcasting (DVB) standards, Integrated Services Digital Broadcasting Standards (ISDB) standards, and standards developed by the Advanced Television Systems Committee (ATSC), including, for example, the ATSC 2.0 standard. The ATSC is currently developing the so-called ATSC 3.0 suite of standards. The ATSC 3.0 suite of standards seek to support a wide range of diverse video services through diverse delivery mechanisms. For example, the ATSC 3.0 suite of standards seeks to support broadcast video delivery, so-called broadcast streaming/file download video delivery, so-called broadband streaming/file download video delivery, and combinations thereof (i.e., “hybrid services”). An example of a hybrid video service contemplated for the ATSC 3.0 suite of standards includes a receiver device receiving an over-the-air video broadcast (e.g., through a unidirectional transport) and receiving a synchronized video and closed caption presentation from an online media service provider through a packet network (i.e., through a bidirectional transport). Current proposed techniques for supporting diverse video services through diverse delivery mechanisms and caption services may be less than ideal.